linux-yocto: add iptables legacy kernel config for Docker

Kernel 6.18+ split iptables into legacy/nftables backends. Docker
requires the legacy iptables support, so add the kernel configuration
for the full dependency chain:

- CONFIG_NETFILTER_XTABLES_LEGACY=y
- CONFIG_IP_NF_IPTABLES_LEGACY=m
- CONFIG_IP_NF_FILTER=m
- CONFIG_IP_NF_NAT=m
- CONFIG_IP_NF_TARGET_MASQUERADE=m

Without these, Docker's iptables rules fail to load on 6.18+ kernels.

Signed-off-by: Bruce Ashfield <bruce.ashfield@gmail.com>

1 files changed, 10 insertions, 1 deletions

diff --git a/recipes-kernel/linux/linux-yocto/extra-configs.cfg b/recipes-kernel/linux/linux-yocto/extra-configs.cfg
index a43bbcbc..26f8b0c6 100644
--- a/recipes-kernel/linux/linux-yocto/extra-configs.cfg
+++ b/recipes-kernel/linux/linux-yocto/extra-configs.cfg
@@ -1 +1,10 @@
-# placeholder config fragment for local enable and debug
\ No newline at end of file
+# placeholder config fragment for local enable and debug
+
+# Kernel 6.18+ split iptables into legacy/nftables backends
+# Docker uses legacy iptables, so we need the full dependency chain:
+# NETFILTER_XTABLES_LEGACY -> IP_NF_IPTABLES_LEGACY -> IP_NF_FILTER/NAT
+CONFIG_NETFILTER_XTABLES_LEGACY=y
+CONFIG_IP_NF_IPTABLES_LEGACY=m
+CONFIG_IP_NF_FILTER=m
+CONFIG_IP_NF_NAT=m
+CONFIG_IP_NF_TARGET_MASQUERADE=m
\ No newline at end of file